1. Technical Field
The present invention relates to pressure-regulating valve for regulating the pressure of a liquid fed to a primary chamber via an inflow port and feeding the liquid from a secondary chamber via an outflow port; and to a liquid droplet ejection apparatus that is provided with the pressure-regulating valve.
2. Related Art
A known pressure-regulating valve of this type for vacuum-feeding a functional liquid from a functional liquid tank to a functional droplet ejection head is disclosed in Japanese Laid-open Patent Publication No. 2006-163733. This pressure-regulating valve is provided with a flat wall portion in which an opening of a communication flow passage on the side of a secondary chamber is formed in the center portion of the flat wall portion, and a conforming wall portion with which a pressure-receiving membrane deformed maximally in the minus direction makes conforming contact, the conforming wall portion being connected to the outside of the flat wall portion via a step portion, and having an outflow opening communicated with an outflow port formed at the bottom of the conforming wall portion.
A valve body is provided to the primary chamber of the communication flow passage, and a protruding shaft provided to the valve body passes through the communication flow passage and makes contact with the pressure-receiving membrane. When the functional droplet ejection head is driven, and the pressure of the secondary chamber decreases, the pressure-receiving membrane is concavely deformed, and the valve body opens via the shaft. The functional liquid thereby flows into the secondary chamber from the primary chamber, and as the pressure of the secondary chamber increases, the pressure-receiving membrane returns to the original state, and the valve body closes. By repeating this process, the functional liquid is vacuum-fed at a predetermined pressure to the functional droplet ejection head. In this pressure-regulating valve, a groove that extends vertically or in a cross shape is formed so as to extend from the flat wall portion to the conforming wall portion so that the functional liquid flows smoothly from the communication flow passage to the outflow port when the pressure-receiving membrane is deformed maximally in the minus direction.
During initial filling of the pressure-regulating valve described above, the functional liquid is forcibly suctioned from the secondary chamber via the functional droplet ejection head. Specifically, in the state in which the secondary chamber is depressurized to deform the pressure-receiving membrane maximally in the minus direction and open the valve body, and the pressure-receiving membrane is conformed to the conforming wall portion, the liquid flows in from the primary chamber to the secondary chamber via the communication flow passage (secondary-chamber-side opening).
However, the pressure-regulating valve described above has drawbacks in that the functional liquid that has flowed into the secondary chamber from the secondary-chamber-side opening flows downward (shortcuts) via the abovementioned groove toward the outflow port that is connected to the suction source, and does not circulate through the top of the inside of the secondary chamber. When the functional liquid shortcuts in this manner without circulating through the top of the secondary chamber, air lingers in the upper space of the secondary chamber, and pressure regulation by the pressure-regulating valve is adversely affected.